This invention relates generally to power transmission elements, such as sprockets, for power transmission purposes and, more particularly, to split power transmission elements, that are mountable on an elongate driven shaft.
Power transmission element, such as gears, pulleys, sheaves and sprockets of various types are used in a variety of applications. In one common application found, for example, in conveyor systems used in the beverage industry, one or more sprockets are mounted on an elongate driven shaft. As the shaft rotates, the sprockets turn to advance the conveyor.
For any number of reasons, it may be necessary to remove or replace a sprocket or other such power transmission element. When conventional one-piece sprockets are used, it is necessary to expose at least one end of the shaft so that the sprockets can be removed or replaced over the exposed end. This is a complicated and cumbersome procedure that can take considerable time and require shutting down conveying operations for an extended period. Valuable production time can thus be lost.
To simplify the repair and replacement of such sprockets, various types of split sprockets have been developed. These sprockets, formed in two or more sections, can be mounted on, and removed from, a driven shaft while the shaft remains in place. Use of such split sprockets greatly simplifies the removal and replacement of the sprocket and reduces the machine "downtime" required to implement maintenance and repair. Such sprockets can be formed of various materials, such as thermoplastic as well as metals. Various means have been developed for fastening the split sprocket mating sections together and the sprocket to the driven shaft.
In one split sprocket arrangement, the sprocket sections are fastened to themselves and to the driven shaft by means of four screw fasteners oriented in planes perpendicular to the shaft. Although effective in clamping the sprocket to the shaft, this arrangement is somewhat complex and difficult to service as at least some of the fasteners are in difficult to reach locations. Furthermore, the use of four separate fasteners on each sprocket increases the likelihood that one or more fasteners will be misplaced during the servicing operation, possibly resulting in use of less than four fasteners or an unanticipated delay before the machine can be returned to service.
Another split sprocket arrangement includes two fasteners that lie parallel to the longitudinal axis of the driven shaft. Although only two fasteners are used, the orientation of the fasteners parallel to the shaft makes it difficult to reach the fasteners, particularly if the sprocket is near the machine housing or the machine frame is adjacent the shaft end. Furthermore, in such a coupling arrangement the fasteners develop no force in the direction toward the shaft and hence do not provide the clamping action that is preferred for securely mounting a sprocket to the shaft.
In view of the foregoing, it is a general object of the present invention to provide a new and improved power transmission element that is easily removed and replaced on a driven shaft.
It is a further object of the present invention to provide a new and improved power transmission element with means for providing a preferentially oriented clamping force for securely mounting the element to the driven shaft.
It is a still further object of the present invention to provide a new and improved split power transmission element that utilizes a minimum of fasteners to simplify installation and removal of the element.
It is a yet another object of the present invention to provide a new and improved split power transmission element that provides convenient access to the fasteners to further simplify installation and removal of the element.
It is a further object of the present invention to provide interlocking power transmission element body teeth for resisting shear forces and aligning the split element portions.
It is an additional further object of the present invention to provide a new and improved split power transmission element that has diagonally disposed fastener sleeves positioned to optimize clamping forces while allowing easy access for service and repair.